This invention relates to a fuel cap and its mounting on the open end of a filler tube for a fuel tank.
Describing a particular use for the cap and filler tube herein disclosed, it is common for large vehicles such as trucks adapted for heavy duty performance to be powered by diesel engines with the fuel for running the engine contained in one or more tanks appropriately mounted on the truck. Fuel is admitted to a fuel tank through what is referred to herein as a filler tube, and a removable cap turned on to the open inlet end of the filler tube closes off the filler tube at times other than when fuel is being admitted to the tank. A number of regulations apply to the type of cap which is provided toward the end of minimizing fuel leakage and fire hazards as a result of collision or other vehicle mishap. One regulation is known as the so-called drop test (where, in effect, a load is dropped a given distance onto a cap closing off a filter tube). The fuel cap after the drop test must continue to maintain an effective seal with the filler tube.
Another consideration is that the fuel cap be able to vent a high pressure condition within a tank caused by high temperature conditions (for instance, a fire), to inhibit explosion of the truck.